Coiling of echogenic perineural catheters with integral stylet: A proof-of-concept randomized control trial in a sciatic nerve block simulator and a pilot study in orthopaedic-trauma patients.

Backround/objectives: We investigated a technique that facilitates the coiling of a regular straight catheter (with integral stylet) behind the sciatic nerve in an ultrasound (US) regional anaesthesia simulator, and then applied our findings to a series of orthopedic-trauma patients.

Methods: We conducted a randomized study of two methods of perineural catheter advancement in a sciatic nerve block Blue Phantom simulator. Two groups of twenty catheters each (method A and method B) were evaluated under real-time ultrasound imaging. The needle in-plane/nerve in-short-axis technique was applied. In method A the catheter was advanced beyond the needle tip with the integral stylet extending along its entire length; in method B the catheter was advanced after its integral stylet was retracted by 6 cm, thus providing flexibility to the catheter's distal end. Additionally, to assess the procedural effectiveness of method B coiling technique, a pilot study was conducted examining 25 perineural catheters coiled underneath the sciatic nerve in trauma-orthopaedic patients to document any catheter tip displacement from their initial position (for 36 hours postoperatively).

Results: In the simulation study, method B led to a significantly higher percentage (18/20:90%) of coiled catheters than method A (3/20:15%). Two coiled catheters of method B were found kinked/obstructed. In our patients, after catheter insertion, the distal end of 2/25 (8%) coiled catheters was obstructed. One perineural catheter was dislodged. For the remaining 22 (88%) catheters, ultrasound imaging demonstrated that local anaesthetic infusion made contact with the sciatic nerve, indicating no displacement of the catheter's distal end postoperatively.

Conclusion: Regular straight perineural catheters can be coiled if their integral stylet is partially retracted. This coiling method offers extra catheter length adjacent to the nerve structure which potentially mitigates catheter tip displacement.

Trial registration: clinicaltrials.gov, registration No: NCT06568510, 23/08/2024, registration URL: https://clinicaltrials.gov/study/NCT06568510?intr=coiling%20of%20echogenic%20sciatic%20nerve&rank=1#study-overview.